Food storage containers

ABSTRACT

A lid for a food storage container includes a lid defining a vacuum sense opening and a vent opening extending through the lid body. The lid also includes a releasable cover disposed over the vent opening to impede air flow into the container through the vent opening until the cover is released. The lid further includes a pressure indicating dome defining a cavity therein, the dome in hydraulic communication with the container through the vacuum sense opening, the dome having a membrane that collapses toward the vacuum sense opening in response to negative container pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of PCT applicationsPCT/EP01/13148, filed on Nov. 14, 2001, PCT/EP01/13233, filed on Nov.15, 2001, and PCT/EP02/14693, filed on Dec. 21, 2002, and claimspriority under 35 U.S.C. § 119(a) from German patent applications DE 10060 999.6 and DE 100 60 995.3, both filed on Dec. 8, 2000, and fromGerman patent application DE 102 30 748, filed on Jul. 9, 2002.

TECHNICAL FIELD

[0002] This invention relates to sealable food storage containers.

BACKGROUND

[0003] Food storage can be improved by keeping food in a container undervacuum. Keeping the food in a container under vacuum helps to protectthe food from certain microorganisms and pests, as well as mold andfungus growth. Furthermore, it helps prevent the food from oxidizing,thereby maintaining the moisture level and aroma of the food. However,with systems of this type it is often difficult to open the storagecontainer because the vacuum inside the container draws on the containerlid. In addition, it is often not possible for the user to recognizewhether the desired vacuum is still present in the storage container.Furthermore, it can be difficult to maintain an adequate vacuum in thestorage container, particularly over a prolonged period of time.

[0004] Food storage container lids with venting or aerating valves forpressure equalization during heating in a microwave oven are known. Forexample, EP 0 633 196 A2 describes a mechanism of this type. The ventingor aerating valves can be used to prevent the build-up of overpressurein the interior of a food storage container when it is heated. Such abuild-up of overpressure typically occurs when there are aqueous liquidsin the interior of the container, and the liquids evaporate duringheating, thereby building up an overpressure in the container interior.The result can be that sauces or other food within the container canspurt out suddenly when the container lid is opened. EP 0 633 196 A2proposes a venting valve in the lid of the food storage container. Theventing valve is to be opened before the container is placed in amicrowave oven. The water vapor which develops during heating can thenescape unhindered through the valve, without a corresponding build-up ofvapor pressure in the interior of the sealed container. It is notintended to achieve thereby the improved storage of food under vacuum,or the indication of the pressure level in the food storage container.

[0005] In EP 0 820 939 A1, the object is to provide a food storagecontainer with venting capability, so that food stored inside thecontainer can be safely heated in a microwave oven with the containerlid closed. Unlike EP 0 633 196 A2, a valve mechanism is described whichcan be opened by way of a joint like a rocker. Hence all that isrequired is to press in the rocker lever for the valve to open withease. Here, too, there is no intention to use the valve mechanism toimprove the storage of food under vacuum or to indicate the pressurelevel in the food storage container.

[0006] EP 0 644 128 A1 describes a food storage container having acontainer lid with a recess in which several vent openings are formed.The vent openings are closed by a seal when a vacuum exists in theholding space. The seal has pin-shaped anchor bars which projectupwardly a small amount out of the recess and grow thicker at theirends. These anchor bars serve to lift the seal off the vent openingswhen air is to enter the holding space of the storage container fromoutside. Relatively high manual forces need to be applied to open thisvalve.

[0007] WO 88/00560 describes an opening mechanism for a plastic beveragecan, and allows for a kind of visual check of pressure level. Thebeverage can has a plastic lid (the lids involved tend to be plastic,since one object is to avoid using metal lids) which bulges outward whenthe pressure inside the container is above atmospheric pressure. Such anarrangement does not allow for any quantitative conclusions about themagnitude of the pressure above atmospheric inside the container.Pressure equalization can occur by opening a venting valve, making iteasier to subsequently remove the entire lid. The equalization ofoverpressure in the container interior (as a result of carbonatedbeverages, for example) plays a role in this case. This openingmechanism does not, however, allow for re-closure and the correspondingbuild-up of pressure.

[0008] CH 304 374 discloses a closure lid for an aluminum sterilizingcontainer. The lid has an essentially circular-ring-shapedconfiguration, and is mounted on a cylindrical aluminum container. Arubber seal is placed between the edge of the lid and the upper brim ofthe container. In the middle of the container lid there is an additionalopening which is covered by a rubber cap. The rubber cap provides avisual check, indicating whether there is a vacuum inside the container.As long as the pressure inside the container is adequately belowatmospheric pressure, the rubber cap bulges inward a correspondingamount. This bulge diminishes continually as the vacuum decreases. Henceit is difficult for the observer to decide whether the pressure levelinside the container is adequate for ensuring the freshness of the foodinside the container.

[0009] Finally, DE 100 60 999 C1 describes a food storage containerincluding a container lid with an opening mechanism for ventilating theevacuated container before it is opened. According to one embodiment, asealing tongue is raised up from a vent via a driver. The sealingmembrane and a pressure indicator are fastened directly on the containerlid. The opening tab is connected non-releasably to the container lidvia a film hinge. This mechanism provides an improved possibility forstoring food under vacuum. The opening of the lid is facilitated byprior ventilation and the pressure indicator indicates the state ofpressure in the container interior. However, disadvantages of thismechanism include the costly installation of the sealing componentsdirectly on the container lid, and the complicated driver mechanism ofthe one-way valve, which is susceptible to defects. Furthermore, thepossibility of exchanging the valve mechanism is limited.

SUMMARY

[0010] In one aspect, the invention features a lid for a food storagecontainer. The lid includes a lid body defining a vacuum sense opening.A vent opening extends through the lid body. The lid also includes areleasable cover disposed over the vent opening. The cover impedes airflow into the container through the vent opening until the cover isreleased. The lid further includes a pressure indicating dome. Thepressure indicating dome defines a cavity, and is in hydrauliccommunication with the container through the vacuum sense opening. Thepressure indicating dome includes a membrane that collapses toward thevacuum sense opening in response to negative container pressure. Oneadvantage of this lid and of the pressure indicating dome is that theycan be easy and economical to manufacture. The pressure indicating domecan permit simplified evacuation of a container by allowing the user toimmediately see when a sufficient vacuum has been attained inside thecontainer. The pressure indicating dome can provide a visual and/ortactile signal of the status of the pressure inside the container.

[0011] The visual impact of the membrane of the pressure indicatingdome, which can be made of an elastomeric plastic material, can beincreased by, e.g., designing the membrane in an easily visible color.Such an embodiment can allow for particularly easy viewing of thepressure indicating dome, as well as a clear indication of the pressurein the food storage container.

[0012] Another advantage of the pressure indicating dome is that it canenable even users with poor vision to determine the condition ofpressure inside a storage container through tactile means (e.g., bydetermining the degree to which the pressure indicating dome projectsbeyond, or disappears within, the outer contour of the cover).

[0013] In some embodiments, the lid further includes a resilient layerthat is in contact with the membrane. The resilient layer can include aspring sheet and/or an elastomeric polymer. The resilient layer can beformed, for example, by selecting a suitable resilient plastic materialfor the membrane of the pressure indicating dome or by inserting aspring metal in the membrane of the pressure indicating dome. Anadvantage of this embodiment is that when the interior of the storagecontainer is at ambient pressure, the membrane of the pressureindicating dome can project distinctly outward.

[0014] In some cases, the pressure indicating dome is capable ofindicating two discrete states: (1) the interior of the storagecontainer being at a pressure that is sufficiently below atmosphericpressure, and (2) the interior of the storage container being at apressure that is insufficiently below atmospheric pressure. An advantageof this embodiment is that the pressure indicating dome can adopt anumnistakable signal position. In other words, if a pre-defined pressurebelow atmospheric pressure is attained inside the container, then themembrane can “snap” inward. In some cases, e.g., when the membraneincludes a spring, the membrane can be guaranteed to snap back into itsinitial position when a minimum pressure below atmospheric is exceededinside the storage container. In such cases, the pressure indicatingdome can have only two unmistakable positions: sufficient pressure belowatmospheric inside the storage container (the pressure indicating domeis snapped inward), and insufficient pressure below atmospheric orambient pressure (the pressure indicating dome is in its initialposition).

[0015] In some cases, the pressure indicating dome has an essentiallycup-shaped configuration with a planar top adjoined by a conicallywidening annular wall. Such an embodiment of the pressure indicatingdome can allow for a clear indication of good or poor vacuum in thecontainer interior. It can avoid a gradual shifting motion by thepressure indicating dome. The annular wall can be slightly outwardlydomed, which can allow the pressure indicating dome to be foldedtogether with particularly little friction. There can be no notablerubbing of the side wall when the pressure indicating dome is rolledtogether.

[0016] In certain embodiments, the cover also defines an indicatoropening. Under certain pressure conditions, the membrane extends throughthe indicator opening. A benefit to this embodiment is that the pressureindicating dome can penetrate the indicator opening as soon as thevacuum in the container interior is inadequate (without penetrating theindicator opening when there is sufficient vacuum in the containerinterior).

[0017] In some cases, the membrane is formed of a plastic resin. Theplastic resin can be selected to maintain dimensional stability of themembrane over a temperature range between about −40° C. and about 100°C. An advantage to this embodiment is that it can allow the storagecontainer and its contents to be stored in a freezer and later to bedefrosted in a microwave oven.

[0018] In some embodiments, the lid includes a one-way valve. Theone-way valve can include a movable sealing tab. The pressure indicatingdome can be integrally connected with the one-way valve (e.g., thepressure indicating dome can be integrally connected with the movablesealing tab). In such cases, the integral one-piece constructionincluding the pressure indicating dome and the one-way valve can includea relatively stiff material and/or a material possessing sealingproperties. An advantage of this embodiment is that it can be economicalto manufacture (e.g., as an injection molding). Furthermore, it can beeasily mounted on the storage container.

[0019] In some cases, the components of the valve device are providedseparately from the food storage container, and are removably fastenedto the food storage container. Advantages of such an embodiment caninclude simple installation during production and/or the repair orexchange of defective components. Furthermore, the components do notneed to be assembled at their site of manufacture.

[0020] In some embodiments, the cover is pivotably connected to the lidbody by a hinge. The hinge can be formed integrally on, e.g., the lidbody. The hinge can be of a material with inherent springcharacteristics, which can enable the hinge simply to be snapped into ahinge holder fitted, for example, to the lid body.

[0021] The pressure indicating dome can include a spring. The stiffnessof the spring can be set or selected retrospectively to the desiredresponse pressure (i.e. to the value of the container pressure at whichthe pressure indicating dome is triggered). The pressure indicating domecan include a resilient material. An advantage to such a pressureindicating dome is that it can have a low number of required componentsand it can be simply installed.

[0022] In some cases, the cover is produced by an injection moldingprocess.

[0023] In another aspect, the invention features a lid for a foodstorage container. The lid has a lid body with a vent opening in it, anda releasable cover disposed over the vent opening. The releasable coverimpedes air flow into the container through the vent opening until thecover is released. The releasable cover has an evacuation opening. Thelid also includes a membrane that covers the vent hole until the coveris released. The lid further has a driving element that is connected tothe membrane at one end and disposed within the evacuation opening atanother end.

[0024] The lid can have the advantage of being easy and economical tomanufacture. Further, the lid can be opened easily because the membrane,which simply rests on the vent hole, can be lifted off the vent hole bypulling open the cover by way of the driving element. This operation canbe comfortably performed without any particular effort because of theleverage between the cover, the driving element and the sealing tab.This can result in pressure equalization between the interior of thecontainer and the surroundings. The container lid is no longer drawn bythe vacuum in the interior of the storage container and can be liftedoff it with ease. It is also possible for the opening assembly to bepositioned in the upper area of the outer wall of the container, aboveits maximum filling level, such that no food is sucked into the vacuumpump when air is evacuated from the storage container.

[0025] In some embodiments, the membrane is of an elastomeric plasticand/or acts as a one-way valve. The membrane can be constructed as arectangular plastic strip, for example, with one narrow side connectedto the container lid body or an elastomeric plastic layer attachedthereto. This fastening edge can act as an elastic joint. During theevacuation operation the membrane can be swiveled upward from the ventopening by the suction effect of the suction device, i.e., the membranecan be lifted clear of the vent opening, enabling air present in thestorage container to be drawn off by the suction device. Once thestorage container is evacuated, sealing can take place automatically bythe membrane being drawn against the vent opening in the lid body.

[0026] The membrane can be a sealing tab.

[0027] In some cases, the driving element has a rim. This can allow fora simple connection of the driving element to the cover without theparts being joined together by way of threaded connections or any otherspecial connecting elements. If the driving element is elastically madeof plastic, the rim can be elastically squeezed together and pushedthrough the evacuation opening in the cover so that subsequently the rimcovers the evacuation opening and can no longer slip through theevacuation opening.

[0028] In some embodiments, the cover can be pressed into a recess ofthe lid body and locked in the recess for the storage state of thestorage container. It can thus be easily possible for several storagecontainers with their storage lids to be stacked on top of each otherwithout the cover projecting in obstructing manner from the upper sideof the container lid body. The lid can include a recessed grip such thatit can be possible, even if the cover is clipped in place within arecess of the container lid body, for a user to grip in the gap with onefinger in order to lift the cover. The grip surface can be oriented atan upward angle, away from the container lid body.

[0029] The driving element can be integrally connected to the membrane.The driving element can be constructed, for example, as a spigotstanding essentially perpendicular on the membrane, with acircumferential edge positioned in its upper area. In this arrangementthe driving element can be made of an elastic material.

[0030] In certain embodiments, the cover has a surface that extendsabout the evacuation opening and that is adapted to receive a sealinglip of a vacuum pump.

[0031] In some cases, the lid body is of a plastic resin (e.g.,polypropylene, polyamide, and/or other temperature- and aging-resistantplastic materials) that is selected to maintain dimensional stability ofthe membrane over a temperature range of between −40° C. and 100° C. Insuch cases, it can be possible for the storage container and itscontents to be stored in a deep-freezer and then to be defrosted in amicrowave oven. The vent opening can be opened by way of the cover forheating in a microwave oven. Possible materials are polypropylene andpolyamide as well as any other temperature- and aging-resistant plasticmaterial.

[0032] The lid body can further include a pressure indicator.

[0033] In some cases, the container lid body and the cover can bemanufactured as a joint injection molding. The cover can be integrallyconnected to the lid body by a hinge. For the membrane and the pressureindicator, it is possible to use an elastomeric plastic or rubbermaterial, which can then be inserted with a sealing effect in thecomponent made up of the container lid body and the cover.

[0034] The lid can be universally used with different food storagecontainers. If the vent assembly is positioned on the container, thenthe outer surface of the cover adjacent the evacuating openingpreferably faces at an angle in an upward direction in order to bebetter able to mount a vacuum pump on the container wall. This can alsofacilitate the handling of the vent assembly.

[0035] Implementations of the invention can have one or more of thefollowing advantages. The pressure indicator and/or the opening andclosing mechanism of the storage container can be easy and inexpensiveto manufacture. The storage container can be opened without any majoreffort. In some cases, only the smallest possible forces are needed tocause the membrane to lift off of the vent opening and to reduce thevacuum inside the storage container. Uncontrolled spraying of food outof a vent opening due to overpressure can be minimized. As a result, thelikelihood of a user being soiled and/or scalded when using thecontainer can be reduced.

[0036] The cover can perform several functions, and thereby save spaceand cost. In other words, the cover can act as a coupling element forreceiving and forming a tight connection with a vacuum pump, as anactuating and opening element for the one-way valve formed together withthe membrane and the vent opening, and/or as an impact guard for thecontainer lid.

[0037] The pressure indicating dome can allow a user to immediately seewhen there is a sufficient vacuum inside a storage container. Thepressure indicating dome can provide a visual and/or tactile signal ofthe pressure condition inside a storage container. The membrane of thepressure indicating dome can include, e.g., an elastomeric plasticmaterial which can be of an easily visible color. The pressureindicating dome can enable a user with poor vision to determine thecondition of pressure inside the storage container by means of touch. Alid with a pressure indicating dome can serve as a multi-functioncomponent.

[0038] The valve device can have the advantage of being simple to fitand having few components. The valve device can be exchanged or fixed(if, for example, a leakage or the like suddenly occurs). The valvedevice can be multifunctional, simultaneously providing a connection fora vacuum pump, pressure indication, and ventilation.

[0039] The details of one or more embodiments of the invention are setforth in the accompanying drawings and the description below. Otherfeatures and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

[0040]FIG. 1 is a schematic cross-sectional view of a first valve devicefor a food storage container when there is an insufficient vacuum insideof the container.

[0041]FIG. 2 is a schematic cross-sectional view of the valve device ofFIG. 1, when there is a sufficient vacuum inside of the container.

[0042]FIG. 3 is a schematic cross-sectional view of the valve device ofFIG. 1, when the inside of the storage container is at atmosphericpressure.

[0043]FIG. 4 is a perspective view, partially in cross-section, of asecond valve device for a food storage container, when there is aninsufficient vacuum inside of the container.

[0044]FIG. 5 is a perspective view, partially in cross-section, of thevalve device of FIG. 4, when a vent has been opened in the storagecontainer.

[0045]FIG. 6 is a perspective view of a food storage container includingthe valve device of FIG. 4.

[0046]FIG. 7 is a schematic cross-sectional view of a third valvedevice, in the fitted state.

[0047]FIG. 8 is a perspective exploded view of the valve device of FIG.7.

[0048]FIG. 9 is a perspective view of a fourth valve device, in thefitted state.

[0049]FIG. 10 is a perspective exploded view of the valve device fromFIG. 9.

DETAILED DESCRIPTION

[0050] Referring to FIGS. 1-3, a valve device 1, which is engageablewith a food storage container 15, includes a pressure indicator 6.

[0051] Referring now to FIGS. 1-6, valve device 1 is mounted on acontainer lid 2. A cover 7 is integrally connected to container lid 2 bymeans of a film hinge 32. Cover 7 and container lid 2 are injectionmoldings made of temperature-resistant thermoplastic material. Cover 7,which in the plan view can be in the form of an oval plate, includes aconnecting device 9. Connecting device 9 allows container lid 2 toreleasably engage a vacuum pump—i.e., connecting device 9 provides asuction port for a vacuum pump. Connecting device 9 is formed by asmooth annular surface 18 on the outer side 210 of cover 7, and by oneor more openings 17 within annular surface 18. A suitable connectingdevice is described in a U.S. patent application filed concurrentlyherewith, entitled “Food Storage Containers” and assigned Ser. No.______, the entire contents of which are hereby incorporated byreference.

[0052] A sealing tab 3 (of, e.g., elastomeric plastic) is disposed onthe lower side of cover 7, underneath connecting device 9. In the valvedevice 1 shown in FIGS. 1-3, sealing tab 3 is fastened to cover 7 by acircular-ring-shaped bar 19, and is a separate component in the shape ofa disk. Bar 19 has an air passage 30.

[0053] In FIGS. 1-6, cover 7 is inserted in a recess 20 in container lid2. Recess 20, which is essentially rectangular, is adapted to conform tocover 7. Container lid 2 includes a vent hole 4 under connecting device9 of cover 7, and under sealing tab 3. When open, vent hole 4 provides aconnection between the atmosphere and the interior 22 of storagecontainer 15. When closed, vent hole 4 is closed air-tight by sealingtab 3. Vent hole 4 and sealing tab 3 together form a one-way valve 40,which closes in the direction of storage container 15.

[0054] A vacuum sense opening 5 in container lid 2 is arranged adjacentto vent hole 4. Pressure indicator 6 includes a plastic membrane 220which provides an air-tight covering for vacuum sense opening 5.Pressure indicator 6 extends in an upward direction, essentiallyperpendicular to the plane of container lid 2. When there is aninsufficient vacuum in the container, the entire pressure indicatorprojects upward relative to the plane of container lid 2. In otherwords, pressure indicator 6 displays an essentially cup-shaped andslightly outwardly domed side wall 23, which tapers in an upwarddirection and terminates with a horizontally extending circular base 24,as shown in FIGS. 1 and 3-5. Referring specifically to FIGS. 2 and 4,top 24 has a diameter “D” which is smaller than the diameter “d” of theopening on base 25 of pressure indicator 6. As shown in FIG. 2, sidewall 23 of pressure indicator 6 folds into a cavity 26 (FIG. 1) in thepressure indicator when exposed to vacuum.

[0055] Referring to FIGS. 1-6, cover 7 includes an indicator opening 8at the position of pressure indicator 6. When the pressure in interior22 of storage container 15 is not sufficiently below atmosphericpressure, pressure indicator 6 extends vertically out of indicatoropening 8, past the outer surface 33 of cover 7. Pressure indicator 6can be made of an elastomeric plastic. Preferably, pressure indicator 6is of an easily visible color, such as red (to, for example, distinguishit from the surrounding material of the lid). In FIGS. 1-3, pressureindicator 6 is reinforced on its inner side by a layer 12 thatpreferably includes a resilient material, such as a spring sheet orelastomeric plastic. The surface of layer 12 is engaged with the innerside 34 of the pressure indicator 6.

[0056] In FIGS. 1-6, the section of cover 7 that is closest to the edgeof storage container 15 has a gripping surface 10. For example, as shownin FIGS. 1-6, an end of cover 7 is beveled slightly upward starting atpoint 35, thereby forming gripping surface 10. Container lid 2 includesa recess 20 with a bottom 37. Cover 7 is separated from bottom 37 ofrecess 20 by ribs 29 and 36. Thus, gripping surface 10 of cover 7 can becomfortably gripped between a user's finger and thumb (not shown) andpulled open in an upward direction.

[0057] FIGS. 1-3 show a retaining clip 11 which presses the elastomericplastic material of the planar base 25 of pressure indicator 6 againstcontainer lid 2. Retaining clip 11 is supported by walls of containerlid 2 (not shown). In FIGS. 1-3, cup-shaped pressure indicator 6 isintegrally connected to base 25. Thus, when pressure indicator 6 isclamped by retaining clip 11, the pressure indicator effectively issealed to container lid 2.

[0058] Referring to FIGS. 4-6, a second example of a valve device 1 alsoincludes a pressure indicator 6 for a food storage container 15. In thevalve device 1 of FIGS. 4-6, cover 7 is again integrally connected tocontainer lid 2 by means of a film hinge 32. Sealing tab 3 is arrangedunderneath connecting device 9 of cover 7. Sealing tab 3 is connected tocover 7 by a driving element 13. Sealing tab 3, driving element 13, base25, and pressure indicator 6 all are made of a single elastomericplastic part which is fastened as an insert to a bead 21 in recess 20 ofcontainer lid 2. The plastic material used for pressure indicator 6 hasspring-like properties, such that pressure indicator 6 can snap into aposition that indicates whether there is a sufficient vacuum inside thecontainer.

[0059] Thus, there are some differences between the valve device 1 ofFIGS. 1-3 and the valve device 1 of FIGS. 4-6. In FIGS. 1-3, sealing tab3 forms a separate sealing part relative to pressure indicator 6. In thevalve device 1 of FIGS. 4-6, on the other hand, these parts are formedby a single elastomeric component—sealing tab 3 is partially cut out ofbase 25, thereby forming a gap 28. Furthermore, in FIGS. 4-5, acircumferential seal 14 is disposed around the edge of container lid 2.Seal 14 enables lid 2 to be closed air-tight against storage container15. In FIGS. 1-3, on the other hand, lid 2 itself forms a tight closurewith storage container 15 (i.e., there is no circumferential seal 14).

[0060] Referring back to FIGS. 4-6, when valve device 1 is closed,circumferential rib 29 presses base 25 against the bottom 37 of recess20, thus effecting a seal. In FIGS. 1-3, base 25 is pressed againstcontainer lid 2 by retaining clip 11, which is fitted to lid 2 bylatching. In FIGS. 4 and 5, cover 7 performs the same function asretaining clip 11 does in FIGS. 1-3, so that there is no need for aseparate retaining clip.

[0061] Another difference between the valve device 1 of FIGS. 1-3 andthat of FIGS. 4-6 is that the valve device shown in FIGS. 4-6 includesdriving element 13, while the valve device shown in FIGS. 1-3 does not.

[0062] In FIGS. 1 and 3-6, the pressure in the interior 22 of storagecontainer 15 is equal to ambient pressure. Because of its spring bias,pressure indicator 6 thus projects out through indicator opening 8 andbeyond cover 7.

[0063] In FIG. 2, there is sufficient vacuum in the interior 22 ofstorage container 15. Pressure indicator 6 is thus drawn into cavity 26,toward container interior 22. The pressure indicator is in a folded orsnapped-in condition. In this state, pressure indicator 6 either doesnot project at all beyond the outer contour of cover 7, or else projectsbeyond the outer contour by a negligible amount. Pressure indicator 6folds like a rolling membrane. The ratio of diameter “D” to diameter “d”is selected based on the wall thickness “f” and the elastic material ofpressure indicator 6, so that pressure indicator 6 will abruptly foldtogether when there is a sufficient vacuum in the interior of thecontainer (as shown in FIG. 2). If the vacuum in container interior 22decreases, then at the point of insufficient vacuum, pressure indicator6 will make an abrupt outward movement, snapping back into the positionshown in FIGS. 1 and 3-6. Thus, gradual shifting of pressure indicator 6is avoided, and the user has a clear indication of whether there is asufficient vacuum in the container.

[0064] A user can first inform himself about the pressure status incontainer interior 22 by checking the position of pressure indicator 6when container lid 2 is closed. If the bottom of pressure indicator 6projects out through indicator opening 8, then the pressure in containerinterior 22 is insufficient for guaranteeing the storage of food undervacuum conditions (as is the case in FIGS. 1, 4, and 6).

[0065] In FIGS. 1, 3, and 6, storage container 15 is evacuated. Toevacuate the container, a suction port with a circumferential sealinglip of a vacuum pump (not shown) is placed on connecting device 9 ofvalve device 1. Then, the vacuum pump is put into operation, causingvent hole 4 of valve device 1 to automatically open. Vent hole 4 opensbecause the suction effect of the vacuum pump causes sealing tab 3 tolift off from vent hole 4, and the air contained in storage container 15is drawn off by the vacuum pump. In FIG. 1, the air is drawn throughvent hole 4, past the side of sealing seat 38 of sealing tab 3, aroundthe outside of sealing tab 3, through air passage 30, and throughconnecting device 9 to the vacuum pump. As shown in FIG. 2, when asufficient vacuum is attained in the interior 22 of storage container15, pressure indicator 6 suddenly snaps inward, thereby informing theuser that he can end the evacuation operation. After the vacuum pump isdisengaged from connecting device 9, sealing tab 3 is pressed againstthe edge of vent hole 4, automatically closing it air-tight. Thisoperation also occurs with each return stroke of the vacuum pump, inorder to enable a vacuum to be built up in interior 22. The vacuum ininterior 22 keeps enclosed food fresh for a long time because lack ofoxygen prevents the food from being oxidized.

[0066] To remove food from storage container 15, the user grips cover 7with two fingers under gripping surface 10 and, with little force,swivels cover 7 in a counterclockwise direction (as shown in FIG. 5).Referring to FIG. 3, sealing tab 3 is thus lifted by cover 7 in anupward direction, off sealing seat 38, and vent hole 4 is cleared. Inthe valve device 1 shown in FIG. 5, the upper side of cover 7 firstcomes up against the lower side of a rim 230 formed on driving element13. The upper side of cover 7 then pulls driving element 13 and sealingtab 3 upward, until sealing tab 3 lifts off from sealing seat 38 andswivels upward in a counterclockwise direction. Referring to FIGS. 3 and5, air can now flow into container 2 via vent hole 4. The distance 5between rim 230 and the upper side of cover 7 is sufficiently large toprevent the upper side of cover 7 from striking rim 230 until aftercover 7 has been released from the latching arrangement (not shown) inrecess 20. Such a structure helps to keep the actuating forces low.

[0067] Container lid 2 can now be removed from storage container 15without any notable effort. In FIGS. 4-5, sealing tab 3, which ispartially separated from the rest of planar base 25 by gap 28, and whichis connected to base 25 only in area 39, repeatedly falls back onto venthole 4 as a one-way valve acting under the force of gravity. Thus, it isrelatively easy to produce a vacuum in the container. It also isconceivable, however, for cover 7 to be designed to snap into place bymeans of clip connectors on container lid 2, thereby enabling sealingtab 3 to close vent hole 4. The material of sealing tab 4 and base 25can be elastic enough as to cause vent hole 4 to be closed a result ofthe closing moment acting on it when there is no difference in pressure.Sealing tab 3 does not lift off vent hole 4 until there is a differencein pressure (i.e., sealing tab 3 works like a one-way valve). Referringto FIG. 3, sealing tab 3 is lifted when cover 7 is swiveled around filmhinge 32 because sealing tab 3 is fastened with clearance to cover 7, inorder to perform the function of a one-way valve.

[0068] Referring to FIG. 6, a thermoplastic food storage container 15includes valve device 1 from FIG. 4. Storage container 15 has acontainer body 16 in the shape of a right-parallelepiped and, whenviewed from the top, has an essentially rectangular container lid 2 witha circumferential rim 27. Valve device 1 is arranged in a recess 20 onone of the narrow sides of container lid 2. Gripping surface 10 of cover7 terminates approximately with outer surface 33 of container lid 2.When there is insufficient vacuum inside of the container, only pressureindicator 6 projects vertically out of indicator opening 8 of cover 7.

[0069] Adjacent to pressure indicator 6 are connecting device 9 (e.g., acircular connecting device), with smooth annular surface 18, andevacuation hole 17, from which driving element 13 projects with its rim230. Rim 230 improves the driving effect of driving element 13 whencover 7 is swiveled upward. Through the leverage produced by distances“R” and “r” (shown in FIG. 5), relatively little manual force “F” (shownin FIG. 4) needs to be applied to grip surface 10 and lift sealing tab 3from sealing seat 38, even when there is still a vacuum in interior 22of the container. As distance “r” becomes smaller and distance “R”becomes larger, it becomes easier to open valve device 1.

[0070] When the valve device is assembled, the upper area of the drivingelement can be pushed with the rim through evacuation hole 17, with therim being elastically squeezed together until it has penetrated theevacuation hole from the bottom up. Thereafter, the rim can widen andact as a sort of barb. When cover 7 is swiveled open, driving element 13is moved upward over the rim in a curved path. The loose end of thesealing tab which is connected to the driving element is thus movedlikewise in an upward direction, and lifted clear of the vent hole.

[0071] Because of the distance between the lower side of the drivingelement rim and the upper side of the evacuation hole, the drivingelement initially slides through the evacuation hole when the cover isswiveled. The rim does not abut and take support upon the upper side ofthe cover until after the cover has executed a certain swiveling motionabout the bearing point, preferably in a counterclockwise direction.From this moment on, the distance between the lower side of the coverand the upper side of the container lid is large enough for severalfingers to grip underneath the cover. Thus it is possible, with greaterforce if at all necessary, to lift the sealing tab off the vent hole bythe cover, moving the driving element (and hence the sealing tab) in anupward direction.

[0072] The fact that the driving element extends with a clearance inevacuation hole 17 and is also elastically deformable within certainlimits means that the swivel movement of the cover on the drivingelement is deflected in a direction of force extending essentiallyperpendicular to the sealing surface of the valve opening, with theresult that only a small valve opening force is needed to cause thesealing tab to lift off the valve seat of the vent hole and to relievethe vacuum inside the storage container.

[0073] The cross-section of the rim of the driving element preferably isdimensioned sufficiently large for the rim to display adequate rigidity,and not to slip through the evacuation hole when the cover is pulledopen. It is preferable instead for the rim to rest on the upper side ofthe cover, and for the sealing tab to reliably lift clear of the venthole even in the presence of vacuum in the container interior.

[0074] In FIGS. 7 and 8, a first example of a valve device 101 is in thefitted, opened state. Valve device 101 is fitted to a container lid 109of a storage container 121 for food. Valve device 101 can be used toevacuate air from closed container 121, by means of a connection surface115 and an extraction opening 117. Valve device 101 can also be used toventilate evacuated container 121 for easy opening of container lid 109.In addition, the negative pressure in the container is indicated by apressure indicator 113 integrated in valve device 101.

[0075] Container lid 109 sits in the closed state on a container wall108 of storage container 121 and seals the latter in a gas-tight mannertogether with a container seal 107, which is designed as an encirclingflat seal made from elastomeric plastic. Container lid 109 (which can beproduced from thermoplastic) has an elongate depression 126 for holdingvalve device 101. A measuring opening 112 with a circular cross sectionand a vent 111 having a likewise circular cross section are provided indepression 126. Vent 111 is fitted to a frustoconical projection.

[0076] Valve device 101 has a valve housing 104 that can be producedfrom thermoplastic. Valve housing 104 has an elongate shape which tapersin one direction and has rounded ends and an encircling edge 123. Inthis case, a hinge 118 is integrally formed on valve housing 104 at thewider end.

[0077] Encircling edge 123 surrounds a planar plastic surface 127 which,in its wider section arranged level with the vent 111, has a firstcircular cutout 124 concentrically with vent 111. Edge 123, whichvirtually forms an encircling wall, protrudes vertically above and belowplastic surface 127. Furthermore, a second circular cutout 125 isprovided in the narrow section of surface 127, i.e. in the region ofpressure indicator 113.

[0078] Encircling edge 123 provides a boundary and holder for a membrane102. Encircling edge 123 also serves as a clamping connection for avalve housing cover 105. Valve housing cover 105 is likewise producedfrom thermoplastic. The valve housing and the valve housing cover can beconnected to each other by, e.g., a film hinge. Valve housing cover 105has essentially the same outer contour as valve housing 104. Aconnection surface 115 having a lenticular curvature and a centralevacuation hole 117 is provided in the region of first cutout 124. Acircular indicator opening 114 is fitted in valve housing cover 105, inthe region of second cutout 125. Webs which are arranged on the insideof the valve housing cover 105 cause membrane 102 to be pressed againstplastic surface 127 of valve housing 104.

[0079] Membrane 102 is an essentially sheet-like sealing insert whichcan be produced from elastomeric plastic (e.g., polybutadiene,butadiene-styrene polymer, acrylonitrile copolymer, polychlorobutadiene,isoprene rubber, aftertreated polyolefins, polyurethane, or siliconerubber). In some cases, membrane 102 can be produced from natural rubberor cork. Membrane 102 carries out a plurality of functionssimultaneously. First, membrane 102 has, level with vent 111 andevacuation hole 117, a U-shaped incision, what is referred to as sealingtongue 110. Sealing tongue 110 acts as a one-way valve, i.e. sealingtongue 110 raises off from vent 111 during the extraction processundertaken by a vacuum pump (not illustrated) which is fitted toconnection surface 115. As soon as the vacuum pump is removed, sealingtongue 110 closes vent 111 because of the negative pressure produced incontainer 121.

[0080] Second, one region of membrane 102 is designed as a pressureindicator 113 which indicates the vacuum state in the containerinterior. If a sufficient vacuum prevails in storage container 121, theapproximately semispherical pressure indicator 113 is pushed in counterto the pressure of a spring 103 in the direction of container 121,virtually in the manner of a concertina. If a limit value is exceeded orif the pressure between the container interior and surroundings isequalized, pressure indicator 113 is pushed out through indicatoropening 114 by compression spring 103, which is designed as a helicalspring.

[0081] Compression spring 103 is held in a spring holder 119 on valvehousing 104.

[0082] Finally, in the case of the valve device 101 of FIGS. 7 and 8, asealing ring 106 is provided in the region of second cutout 125, saidsealing ring sealing the connection of valve housing 104 to measuringopening 112 in container lid 109.

[0083] After storage container 121 has been filled with food, containerlid 109 is placed onto container wall 108, which is provided with acontainer seal 107. Valve device 101 here is closed, i.e. the food ispacked in a gas-tight manner. A vacuum pump (not illustrated) is nowused to extract the air enclosed in container 121 via evacuation hole117, sealing tongue 110, and vent 111. So that air is exclusivelyextracted from container 121, and not from the surroundings, a sealingedge 122 is formed on membrane 102 and seals the frustoconical elevationaround vent 111. The reaching of the required minimum negative pressurecan be read off using pressure indicator 113. Pressure indicator 113disappears in indicator opening 114 as soon as the required negativepressure is reached.

[0084] When the equalization of pressure occurs over time, the time atwhich a critical point is reached is indicated by pressure indicator113. Pressure indicator 113 is designed, if appropriate, to be colored,and protrudes through indicator opening 114. In other words, pressureindicator 113 is pressed beyond indicator opening 114 by the springforce of spring 103. A spring with an appropriate spring stiffness canbe installed in pressure indicator 113 to help indicate pressureequalization.

[0085] In order to open container lid 109, which is sucked on firmly bythe negative pressure of the container, valve device 101 is grasped athandle 116 and pivoted about hinge 118. This causes sealing tongue 110to be lifted off from vent 111, and sealing ring 106 to be lifted offfrom sealing seat 128. Thus, storage container 121 is ventilated. Afterventilation, container lid 109 can easily be lifted off from container121.

[0086] Referring now to FIGS. 9 and 10, a second example of a valvedevice 101 in the fitted state has essentially three components: valvehousing 104, valve housing cover 105, and membrane 102. Such a structureis possible in particular by the changed design of pressure indicator113, which is produced from a material having inherent spring stiffness.This renders superfluous the compression spring provided in the firstexample of the valve device. In addition, the integration of a sealinglip 121 on the lower edge of pressure indicator 113 saves an additionalsealing ring for sealing the measuring opening 112. Otherwise, theconstruction and the function of the second valve device 101 correspondto that described with reference to FIGS. 7 and 8.

[0087] A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A lid for a food storage container, the lidcomprising: a lid body defining a vacuum sense opening and a ventopening extending through the lid body; a releasable cover disposed overthe vent opening to impede air flow into the container through the ventopening until the cover is released; a pressure indicating dome defininga cavity therein, the dome in hydraulic communication with the containerthrough the vacuum sense opening, the dome comprising a membrane thatcollapses toward the vacuum sense opening in response to negativecontainer pressure.
 2. The lid of claim 1, further comprising aresilient layer in contact with the membrane.
 3. The lid of claim 2,wherein the resilient layer comprises a spring sheet.
 4. The lid ofclaim 2, wherein the resilient layer comprises an elastomeric polymer.5. The lid of claim 1, wherein the cover defines an indicator opening,and wherein the membrane, under certain container pressure conditions,extends through the indicator opening.
 6. The lid of claim 1, whereinthe membrane is formed of a plastic resin.
 7. The lid of claim 6,wherein the plastic resin is selected to maintain dimensional stabilityof the membrane over a temperature range between −40° C. and 100° C. 8.The lid of claim 1, further comprising a one-way valve.
 9. The lid ofclaim 8, wherein the one-way valve comprises a movable sealing tab. 10.The lid of claim 9, wherein the pressure indicating dome is integrallyconnected with the sealing tab.
 11. The lid of claim 1, wherein thecover is pivotably connected to the lid body by a hinge.
 12. The lid ofclaim 1, wherein the pressure indicating dome comprises a spring. 13.The lid of claim 1, wherein the pressure indicating dome comprises aresilient material.
 14. A lid for a food storage container, the lidcomprising: a lid body defining a vent opening therethrough; areleasable cover disposed over the vent opening to impede air flow intothe container through the vent opening until the cover is released, thereleasable cover defining an evacuation opening; a membrane that coversthe vent hole until the cover is released; and a driving elementconnected to the membrane at one end and disposed within the evacuationopening at another end.
 15. The lid of claim 14, wherein the membranecomprises an elastomeric plastic.
 16. The lid of claim 14, wherein themembrane is a one-way valve.
 17. The lid of claim 14, wherein thedriving element defines a rim.
 18. The lid of claim 14, wherein thedriving element is integrally connected to the membrane.
 19. The lid ofclaim 14, wherein the cover defines a surface extending about theevacuation opening and adapted to receive a sealing lip of a vacuumpump.
 20. The lid of claim 14, wherein the lid body comprises a plasticresin selected to maintain dimensional stability of the membrane over atemperature range of between −40° C. and 100° C.